Re: [libvirt] [Qemu-devel] [Qemu PATCH v2] add a boot option to do strict boot

On 01/09/2013 10:52 AM, Amos Kong wrote: > On Wed, Jan 09, 2013 at 08:14:07AM -0700, Eric Blake wrote: >> On 01/09/2013 01:39 AM, Amos Kong wrote: >>> Current seabios will try to boot from selected devices first, >>> if they are all failed, seabios will also try to boot from >>> un-selected devices. >>> >>> We need to make it configurable. I already posted a seabios >>> patch to add a new device type to halt booting. Qemu can add >>> "HALT" at the end of bootindex string, then seabios will halt >>> booting after trying to boot from selected devices. >>> >>> This option only effects when boot priority is changed by >>> bootindex options, the old style(-boot order=..) will still >>> try to boot from un-selected devices. >>> >>> v2: add HALT entry in get_boot_devices_list() >>> define boot_strict to bool >>> >>> Signed-off-by: Amos Kong <akong(a)redhat.com&gt; >>> --- >> Libvirt will need to expose an attribute that lets the user control >> whether to use this new option; how do we probe via QMP whether the new >> -boot strict=on command-line option is available? > > Old style to adjust boot priority by order parameter: > -boot order=n,strict=on (BAD, unselected devices will be tried) > > New style to adjust boot priority by bootindex: > -device virtio-net-pci,...,bootindex=1 -boot strict=on (OK) > > We only want strict option to support new style. > > (those two styles are implemented in two different way insider > seabios, the latest simple patch only changed the bootindex way) Just a note about this: as far as I can tell virt-manager currently only uses the "old style" of specifying boot order; it needs to be enhanced to recognize the presence of bootindex=n ordering, and behave accordingly. Looking from the outside, that looks to be not completely trivial, as the old style of ordering only allows specifying "hard disk" as a single line in the priority order, but the new style has each disk specified separately. Not only that, but *which* of the disks is tried first under the old order may change depending on whether or not a bootmenu is requested (in one case it picks unit=0 on the controller, in the other case, it orders the disks alphabetically by target dev name)